Design for a wristwatch



FIG. 1 is a front elevational view of a wristwatch showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a rear elevational view thereof; and

FIG. 4 is a front elevational view thereof as it appears with its bracelet clasp in a closed condition. 

The ornamental design for a wristwatch, as shown and described. 